Emergency lighting system

ABSTRACT

Battery charge function may be in an LED driver which eliminates the duplication of line interface circuitry. A single line interface circuit provides the input power conversion for both the battery charge function and normal operation of the LED driver. During a loss of power, the LEDs may be controlled using power from the battery backup module.

RELATED APPLICATION

This application claims priority to U.S. Provisional Patent ApplicationNo. 62/005,341 filed May 30, 2014 and entitled “Emergency LightingSystems,” which is incorporated herein in its entirety by thisreference. This application is a continuation of allowed U.S.application Ser. No. 15/794,143, filed Oct. 26, 2017 and entitled“Emergency Lighting System,” which is a continuation of patented U.S.application Ser. No. 14/725,913, filed May 29, 2015 and entitled“Emergency Lighting System,” which claims priority to U.S. ProvisionalPatent Application No. 62/005,341 filed May 30, 2014 and entitled“Emergency Lighting Systems,” each of which are incorporated herein intheir entirety by this reference.

FIELD OF THE INVENTION

This invention generally relates to the field of lighting, specificallyto emergency lighting.

BACKGROUND OF THE INVENTION

The need to provide an emergency path of egress lighting when normalpower is lost is well known. In order to meet this need it is commonpractice to provide some form of battery-powered lighting in a givenspace. It is often convenient and desirable to provide thisbattery-powered auxiliary lighting within the standard or existing lightfixtures. Batteries utilized in these systems are continuously chargedand maintained in a full charge state. Thus, the battery chargingfunction remains turned on and uninterrupted (i.e., unswitched) at alltimes.

In present practice a fluorescent ballast or a light-emitting diode(LED) driver provides for the normal operation of the fixture's lightsource and this device may be switched on and off. A separate batterybackup unit then provides the functions of battery charging, input linevoltage detection, power conversion, load transfer switching and testoperations. This unit, since it contains the battery charging function,remains on at all times and is unswitched.

In the lighting industry, input line voltages typically range from 120volts to 277 volts AC, operating at a frequency of 60 Hz. The input linevoltage is often called line voltage, mains, main power supply, or maininput supply. In some cases, other frequencies and even higher voltagesare utilized, such as 347 volts and 480 volts. Thus the ballast ordriver, as well as the battery backup module, should be capable ofaccepting at least these voltage levels through line interfacecircuitry. It will be understood that this interface to the power mainis critical, and the associated circuitry will be the most vulnerable toexternal phenomenon (e.g., power surges, lightning strikes, equipmentfailures, fluctuations in power, etc). In present practice, there isduplication of the line interface function, since it is present in boththe ballast or driver and the battery backup module. The line interfacefunction is not trivial, and it requires high power factor, transientprotection, electromagnetic interference (EMI) suppression, as well asstart-up accommodations and many other features.

Thus, to reduce cost and the possibility of failure, it is desirable toreduce the quantity of line interface circuits, while maintaining thefull functionality of the battery charging functions and ballast ordriver during both normal operation and emergency operation. It is alsodesirable to increase communication between the ballast or driver andthe battery backup module, to improve both normal and emergencyoperation of the lighting system.

BRIEF SUMMARY OF THE INVENTION

In a first aspect of the invention, the battery charge function may beintegrated into the LED driver. This eliminates the duplication of theline interface circuitry. A single line interface circuit provides theinput power conversion for both the battery charge function and normaloperation of the light source. In this particular implementation the LEDdriver is unswitched, meaning that is it always connected to main power.The LED driver may be of any suitable configuration known to thoseskilled in the art (e.g., two-input or three-input, etc.) The lightingelements, e.g., LEDs are driven by a lighting interface located, invarious implementations, in one or both of the LED driver or batterybackup unit. On/off switching and other control of the light source maybe accomplished in response to other external inputs that may bereceived by the driver or, alternatively, by the battery backup unit.

There are multiple methods of obtaining battery charge current from theLED driver. One method is to provide a separate channel from the driverto the battery backup module, programmed to provide the desired chargecurrent level. As an alternative implementation, charge current may beobtained from a parallel connection with the LED lighting elements, oras a further alternative, from a series connection with the LEDs. Inthese latter two cases special considerations may be given to theeffects of light dimming on the charge current when the dimming functionis to be utilized, and on/off control may be accomplished by a loadtransfer switching scheme that would not affect the charge current.Since the source of the battery charging current is to be energized atall times, and the LED driver may be the source of charge current insome of the described implementations, the on/off switching informationmay be communicated by separate means. This may be accomplished by asimple contact closure, or may be accomplished by a suitable relay,field emission transistor (FET) configuration, control signal inputs asdescribed below, or other switch method known to those skilled in theart.

Other aspects of the invention provide new features for the emergencylighting system. Many of these improvements utilize the capabilities ofan LED driver, such as programmable channels, which allow one channel tobe used for charging a battery backup unit while other channels are usedto drive the LEDs; serialized communications, which allow communicationbetween the battery backup unit and the LED driver and enable on-the-flyadjustments of driver outputs; and dual sourcing of power, which allowsthe LED driver to receive power from the battery backup unit duringemergency operation and power from the main input supply during normaloperation. Many LED drivers also include an external control signalinput which may be used to implement the on/off function, dimming, colorselection, test functions, or other suitable operations apparent tothose skilled in the art. Control signals may be transmitted using 0-10Vvoltage control, DMX, DALI, or any other suitable protocol. It will berecognized by those of ordinary skill in the art that any available orfuture-developed control communication protocol could be used for thissame purpose including, but not limited to, those protocols listed inIllumination Engineering Society publication TM-23-11.

Various implementations of the emergency lighting system may includedirect connections between the LED driver and the lighting elements,wherein the LED driver directly powers the lighting elements duringnormal operation and/or emergency operation. Various otherimplementations of the system may include connections from the LEDdriver to the lighting elements that are passed through the batterybackup module, wherein the battery module may draw charging current fromthe passthrough connections during normal operation. Still furtherimplementations may include connections from the LED driver to thelighting elements that are passed through the battery backup module,wherein the connections pass through for monitoring or test activationwithout providing charge to the battery module.

Normal operation takes place when the mains are providing input linevoltage at an expected level. The expected level will vary as known toone skilled in the art, depending on the use (e.g., residential,commercial, manufacturing, etc.) and geographical region. Emergencyoperation occurs when an interruption (e.g., blackout, brownout,equipment failure, etc.) of the expected input line voltage occurs, andthe mains are unable to supply sufficient input to continue normaloperations. During emergency operations, the number of light sourcesoperated may be none, some, or all of the sources available duringnormal operations, and the sources may be dimmed or otherwise operatedat a reduced output.

The battery backup module may also be identified as the battery backupunit, the battery, or other similar terms as apparent to those skilledin the art. The LED driver module may also be referred to as the LEDdriver unit, the driver, the LED driver, or other similar terms apparentto those skilled in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing an exemplary prior art system in whichboth the battery backup unit and the LED driver include a line interfacecircuit.

FIG. 2 is a block diagram of an exemplary system including a batterybackup unit and an LED driver, where the battery backup unit receivescharging current through the connection to the lighting elements.

FIG. 3 is a block diagram of an exemplary system including a batterybackup unit and an LED driver, where the LED driver provides chargingcurrent to the battery backup unit.

FIG. 4 is a block diagram of another exemplary system including abattery backup unit and an LED driver, where the LED driver providescharging current to the battery backup unit.

FIG. 5 is a block diagram of a further exemplary system including abattery backup unit and an LED driver, where the LED driver providescharging current to the battery backup unit.

FIG. 6 is a block diagram of an exemplary system including a batterybackup unit and an LED driver, where the LED driver provides chargingcurrent to the battery backup unit, and the battery backup unit providesemergency power to the LED driver.

FIG. 7 is a block diagram of an exemplary system including a batterybackup unit and an LED driver, where the LED driver provides chargingcurrent to the battery backup unit, and the battery backup unit providesemergency power to the LED driver, and there is a communication channelbetween the LED driver and battery backup unit.

FIG. 8 is a block diagram of a further exemplary system including abattery backup unit and an LED driver, where the LED driver providescharging current to the battery backup unit, and the battery backup unitprovides emergency power to the LED driver, and there is a communicationchannel between the LED driver and battery backup unit.

FIG. 9 is a block diagram of a yet further exemplary system including abattery backup unit and an LED driver, where the LED driver providescharging current to the battery backup unit, and the battery backup unitprovides emergency power to the LED driver, and there is a communicationchannel between the LED driver and battery backup unit.

FIG. 10 is a block diagram of a yet further exemplary system including abattery backup unit and an LED driver, where the LED driver providescharging current to the battery backup unit, and the battery backup unitprovides emergency power to the LED driver, and there is a communicationchannel between the LED driver and battery backup unit.

FIG. 11 is a block diagram of a yet further exemplary system including abattery backup unit and an LED driver, where the LED driver providescharging current to the battery backup unit, and the battery backup unitprovides emergency power to the LED driver, and there is a communicationchannel between the LED driver and battery backup unit.

FIG. 12 is a block diagram of a yet further exemplary system including abattery backup unit and an LED driver, where the LED driver providescharging current to the battery backup unit, and the battery backup unitprovides emergency power to the LED driver, and there is a communicationchannel between the LED driver and battery backup unit.

FIG. 13 is a block diagram of an exemplary system in which the lineinterface circuit is included in a bulk supply unit that providesunswitched power and charging current to a combination batterybackup/LED driver unit, which drives the lighting elements.

FIG. 14 is a block diagram of an exemplary system in which a combinationbattery backup/LED driver unit is powered by the unswitched mainsvoltage in order to drive the lighting elements and charge, and anadditional battery module may be connected to the combination unit.

FIG. 15 is a block diagram of an exemplary system for obtaining chargecurrent for the battery backup unit via a parallel connection with theLEDs, using a voltage step-down or buck converter.

FIG. 16 is a block diagram of an exemplary system for obtaining chargecurrent for the battery backup unit via a series connection with theLEDs, using a voltage step-up or boost converter to boost the batteryvoltage during emergency operation.

FIG. 17 is a block diagram of an exemplary system for obtaining chargecurrent for the battery backup unit via a series connection with theLEDs, using a shunt control to regulate the charge current and a voltagestep-up or boost converter to boost the battery voltage during emergencyoperation.

DETAILED DESCRIPTION OF THE INVENTION

The implementations of the invention depict various methods orconfigurations to reduce the number of line interface circuits needed,while maintaining or increasing functionality of the exemplary emergencylighting systems. The line interface may be located in the batterybackup module or the LED driver. The lighting interface to connect tothe lighting elements may be included in the battery backup module orthe LED driver module, or, in certain implementations, both modules mayinclude a lighting interface. In some specific implementations, powerfor emergency operations may be supplied from the battery backup throughan input of the LED driver. Charging of the battery may be accomplishedby a dedicated charging output from the driver in some implementations,or by diverting current from the lighting interface in otherimplementations.

In some implementations, control signals from an external sourcedetermining the normal operation of the light elements may be receivedthrough one or more control inputs. Control signals may include on/offinformation, as well as dimming, pulse width modulation (PWM) mode,color selection, test operations, or other options known to thoseskilled in the art. As described above, the control signals may use anysuitable protocol known to those skilled in the art. The control inputsmay also carry status information for the main power supply (e.g., ifthe main power supply is interrupted or not), or depending upon theimplementation, such status information may be received on a separateinput of the battery unit or the driver. This status informationregarding the mains may be used to determine if the lighting system willoperate in emergency mode (e.g., begin using battery backup power) oroperate in normal mode (e.g., continue using power from mains). Besidesthe mains status information, other control signals, including signalsfor test functions, may also be used to determine if the lighting systemwill operate in emergency or normal mode.

Certain implementations may further include control signal inputs andoutputs between the LED driver and battery backup unit. Certain otherimplementations may include a communication channel between the LEDdriver and the battery backup module, for sharing internal stateinformation, adjustments, or other information apparent to those skilledin the art. LED code or other suitable protocols known to the art may beused for communication on the shared communication channel.

In the following descriptions, similar figure numbers are used to referto similar features of the invention implementations.

FIG. 1 is a block diagram showing a prior art system in which the LEDdriver 103 may include a line interface circuit to the main powersupply. The battery backup unit 101 may include a second line interfacecircuit to the main power supply. During normal operation, the LEDdriver controls the LEDs 105 using a lighting interface included in theLED driver. The connections from the lighting interface to the lightingelements 105 may be routed through the battery backup unit 101. The LEDdriver 103 may receive control signal inputs 109 from an external sourceto determine normal operation of the LED lighting element 105, or mayhave an optional on/off switch 111 on the main power line. The batterybackup unit 101 is charged by the main power supply through the secondline interface circuit. Emergency operation may be entered if the mainpower supply no longer supplies power to the battery backup unit 101through the line interface. In emergency operation, the battery backupunit 101 supplies DC power directly to the lighting elements 105 througha second lighting interface. The LED driver 103 is not used.

FIG. 2 is a block diagram of an exemplary system in which the LED driver203 may include a line interface circuit, which may be powered by theunswitched main power supply, to provide charging current for thebattery 201 and detection of loss of the main power. If the lineinterface indicates the main power supply has been interrupted, thesystem may enter emergency operation. An on/off status input 207 to thebattery backup unit 201 may provide status information regarding thedesired on/off state of the lighting elements 205. During normaloperation, the LED driver 203 may drive the lighting elements 205 usingan included lighting interface. The connections from the lightinginterface to the lighting elements 205 may be routed through the batterybackup unit 201, and the battery unit 201 may be charged by a portion ofcurrent diverted from the current driving the lighting elements 205.During emergency operation, the battery unit 201 supplies DC powerdirectly to the lighting elements 205 through a second lightinginterface included in the battery backup unit, and the LED driver 203 isnot used.

FIG. 3 is a block diagram of an exemplary system in which the LED driver303 may include a line interface circuit, which may be powered by theunswitched main power supply, to provide charging current for thebattery 301 and detection of loss of the main power. A status input 307to the LED driver 303 may provide status information of the desiredon/off state of the lighting elements 305. During normal operation, theLED driver 303 may drive the lighting elements 305 using an includedlighting interface. The connections from the lighting interface may berouted through the battery backup unit 301 for testing or linemonitoring; emergency mode may be entered if the line monitoringindicates that the main power supply is interrupted. Charge current forthe battery unit 301 may be obtained through a charging output 302 fromthe driver 303. Control signals for normal operations of the elements305 may be received on control inputs 309 to the driver 303. Duringemergency operation, the LED driver 303 may no longer provide chargingcurrent or mains status information, and the battery backup module 301may drive the elements 305 using a second lighting interface included inthe battery backup module.

FIG. 4 is a block diagram of an exemplary system similar inconfiguration and operation to that shown by FIG. 3, except that in FIG.4 the status input 407 regarding the desired on/off state of thelighting elements 405 is provided to the battery backup module 401.

FIG. 5 is a block diagram of an exemplary system in which the LED driver503 may include a line interface circuit, which may be powered by theunswitched main power supply, to provide charging current for thebattery 501 and detection of loss of the main power. Control signals fornormal operations may be received on control inputs 509 to the batterybackup module 501. The control signals may also be passed through thebattery backup unit 501 to the LED driver 503 using the controlinputs/outputs 510. During normal operation, charge current for thebattery unit 501 may be obtained through a charging output 502 from theLED driver 503. The lighting elements 505 are driven by the LED driver503, using an included lighting interface. The connections from thelighting interface may be routed through the battery backup unit 501 fortesting or line monitoring. Emergency operation may be entered if theloss of charge current on charging output 502 indicates that the mainsupply is interrupted. During emergency operation, the elements 505 arepowered by the battery backup module 501 using a second lightinginterface included in the battery backup module, and the LED driver 503is not used.

Other implementations of the invention include battery backup units thatmay provide emergency power to an intermediate voltage of the LEDdriver. It is common practice for the LED driver to convert the AC powerinput to DC voltage. This DC voltage is an intermediate power supplythat may power the lighting interface(s) of the driver and also theinternal functions of the driver. If the battery backup unit providesthis intermediate power during an interruption in the main power supply,then the LED driver lighting interface may continue to function and mayset the output LED current as desired for a given run time, brightness,and number of lighting elements. In this way the driver retains controlof the LEDs during the power outage. In this implementation, the LEDdriver must recognize the presence of the battery backup power andswitch to an output current consistent with the desired light output andrun-time for the emergency operation.

FIG. 6 is a block diagram of an exemplary system in which the LED driver603 may include a line interface circuit, which may be powered by theunswitched mains voltage to provide charging current for the battery601. A status input 607 may provide the desired on/off state of thelighting elements 605. During normal operation, the LED driver 603 maydrive the lighting elements 605 using an included lighting interface.Charge current for the battery backup unit 601 may be obtained through acharging output 602 from the driver 603. Control signals for normaloperations of the elements 605 may be received on control inputs 609 tothe driver 603. Emergency operation may be entered if the loss of chargecurrent on charging output 602 indicates that the main power supply isinterrupted. During emergency operation, the battery backup unit 601 mayprovide a DC voltage through a voltage output 606 to a connected inputpoint on the driver 603. The LED driver 603 retains direct control ofthe LED elements 605 during emergency operations.

FIG. 7 is a block diagram of an exemplary system in which the LED driver703 may include a line interface circuit, powered by the unswitchedmains voltage to provide charging current for the battery 701. A statusinput 707 may provide the desired on/off state of the lighting elements705. A communication channel 708 may be shared between the LED driver703 and the battery backup module 701. During normal operation, the LEDdriver 703 may drive the lighting elements 705 using an includedlighting interface. Charge current for the battery unit 701 may beobtained through a charging output 702 from the driver 703. Controlsignals for normal operations of the elements 705 may be received oncontrol inputs 709 to the driver 703. Internal information may be sharedbetween the LED driver 703 and the battery backup module 701 oncommunication channel 708. Emergency operation may be entered if loss ofcharge current on the charging output 702 indicates that the main powersupply is interrupted. During emergency operation, the battery backupunit 701 may provide a DC voltage supply through a voltage output 706 toa connected input point on the driver 703. The LED driver 703 retainsdirect control of the LED elements 705 during emergency operations.Communication channel 708 may continue to share information between theLED driver 703 and the battery backup module 701.

FIG. 8 is a block diagram of an exemplary system similar inconfiguration and operation to that shown in FIG. 7, except that in FIG.8 the status input 807 regarding the desired on/off state of thelighting elements 805 is provided to the LED driver 803.

FIG. 9 is a block diagram of an exemplary system in which the LED driver903 may include a line interface circuit, powered by the mains voltageto provide unswitched charging current for the battery 901. A statusinput 907 may provide status information of the desired on/off state ofthe lighting elements 905 to the battery backup unit 901. Acommunication channel 908 may be shared between the LED driver 903 andthe battery backup module 901. During normal operation, the LED driver903 may drive the lighting elements 905 using an included lightinginterface. The connections from the lighting interface may be routedthrough the battery backup unit 901 for testing or line monitoring.Charge current for the battery unit 901 may be obtained through acharging output 902 from the driver 903. Control signals for normaloperations may be received on control inputs 909 to the battery backupmodule 901. The control signals may also be passed through the batterybackup unit 901 to the LED driver 903 using the control inputs/outputs910. Internal information may be shared between the LED driver 903 andthe battery backup module 901 on communication channel 908. Emergencyoperation may be entered if the status information on control inputs 909or communication channel 908 indicates that the main supply isinterrupted. During emergency operation, the battery backup unit 901 mayprovide a DC voltage supply through a voltage output 906 to a connectedinput point on the driver 903. The LED driver 903 retains direct controlof the LED elements 905 during emergency operations. Communicationchannel 908 may continue to share information between the LED driver 903and the battery backup module 901.

FIG. 10 is a block diagram of an exemplary system similar inconfiguration and operation to that shown in FIG. 9, except that in FIG.10 the status input 1007 regarding the desired on/off state of thelighting elements 1005 is provided to the LED driver 1003. The batterybackup unit 1001 receives main supply status information through thecommunication channel 1008 with the LED driver 1003, and/or from theexternal control signals received on control inputs 1009.

FIG. 11 is a block diagram of an exemplary system similar inconfiguration and operation to that shown in FIG. 9, except that in FIG.11, connections from the lighting interface included in LED driver 1103may connect directly to the lighting elements 1105, instead of beingrouted through the battery backup unit 1101.

FIG. 12 is a block diagram of an exemplary system similar inconfiguration and operation to that shown in FIG. 9, except that in FIG.12, connections from the lighting interface included in LED driver 1203may connect directly to the lighting elements 1205, instead of beingrouted through the battery backup unit 1201. Also the status input 1207regarding the desired on/off state of the lighting elements 1205 isprovided to the LED driver 1203, and the battery backup unit 1201receives main supply status information through the communicationchannel 1208 with the LED driver 1203, and/or from the external controlsignals received on control inputs 1209.

Other implementations of the invention are also possible. FIG. 13 is ablock diagram of an exemplary system in which the line interface circuitis included in a bulk supply unit 1317, such as an emergency power bank,an inverter, or any other locally central power supply. Thisimplementation may be used in systems where a DC supply is provided formultiple emergency lighting systems. The line interface circuitryincluded in the bulk supply unit 1317 is powered by the mains voltage toprovide an unswitched power supply for a combination battery backup/LEDdriver unit 1315. A status input 1307 may provide desired on/off statusinformation of the lighting elements 1305 to the combination unit 1315.During normal operation, the dedicated output 1316 from the bulk supplyunit 1317 may provide power for both battery functions and LED driverfunctions of the combination unit 1315. The LED driver components of thecombination unit 1315 may drive the lighting elements 1305 using anincluded lighting interface. Charge current for the battery backupcomponents may be obtained through the dedicated power output 1316.Control signals for normal operations may be received on control inputs1309 to the combination unit 1315. Emergency operation may be entered ifthe status information on control inputs 1309 indicates that the mainsupply is interrupted. During emergency operation, the battery backupcomponents included in the combination unit 1315 may provide a DCvoltage to the included LED driver components, which retain directcontrol of the LED elements 1305.

FIG. 14 is a block diagram of an exemplary system in which the lineinterface circuit is included in the combination battery backup/LEDdriver unit 1415, and may be powered by the mains voltage to provide anunswitched power supply. A status input 1407 may provide desired on/offstatus information of the lighting elements 1405 to the combination unit1415. A separate battery unit 1419 may be included in the exemplarysystem to provide additional power during emergency operation (e.g., topower additional fixtures, brighter elements, fixtures for a longerperiod of time, etc.) During normal operation, the line interfacecircuit may provide power for both battery functions and LED driverfunctions of the combination unit 1415. The LED driver components of thecombination unit 1415 may drive the lighting elements 1405 using anincluded lighting interface. Charge current for the battery backupcomponents included in the unit 1415 may also be obtained through theincluded line interface. The separate battery unit 1419 may also becharged through a dedicated charging output 1414 from the combinationunit 1415. Control signals for normal operations may be received oncontrol inputs 1409 to the combination unit 1415. Emergency operationmay be entered if the status information on control inputs 1409indicates that the main supply is interrupted. During emergencyoperation, the battery backup components included in the combinationunit 1415 may provide a DC voltage to the included LED drivercomponents, which retain direct control of the lighting elements 1405.If the voltage supplied by the battery backup components is notsufficient during emergency operations, the separate battery unit 1419may provide additional power to the combination unit 1415, using poweroutput 1418 from the battery 1419.

FIGS. 15, 16, and 17 are block diagrams representing exemplary systemscapable of deriving charge current for the battery backup module fromthe LED circuit. The systems represented by these figures may beimplemented independently; in conjunction with one of the systemsdescribed above, such as the exemplary system represented by FIG. 2; orin conjunction with a system not described herein.

FIG. 15 is a block diagram of an exemplary system to derive chargingcurrent using a buck converter 1523 (voltage step-down converter) whichis sourced from a higher voltage LED lighting element 1505. The LEDdriver 1503 may receive unswitched power from the main power supplythrough an included line interface circuit. Emergency operation may beentered if the main power supply is detected to be interrupted. Thelighting interface included in the LED driver 1503 may be connected tothe lighting elements 1505 electrically in parallel with the batterybackup components. The lighting elements 1505 may be furtherelectrically in series with an on/off switch 1511, which may be a seriesswitch, relay, FET, or any suitable switching components known to thoseskilled in the art, to provide desired on/off status of the lightingelements 1505.

The battery backup components may comprise a diode 1525 connected inseries from the driver/light element circuit to a capacitor 1526 and theconverter/battery subcircuit. The capacitor 1526 and theconverter/battery subcircuit may be connected in parallel. Theconverter/battery subcircuit may be comprised of a battery 1521connected as an electrical output load of a buck converter 1523. Thebuck converter 1523 may be implemented using microprocessor control forvarious charging algorithms, as apparent to those skilled in the art.During normal operation, the driver 1503 may drive the lighting elements1505, while the converter 1523 may supply the desired charge current tothe battery 1521. The converter 1523 may retain the peak voltagesupplied by the included lighting interface of the LED driver 1503, evenif the lighting elements 1505 are dimmed or operated in a PWM mode.During emergency operation, charging of the battery backup module 1501may cease, and the battery 1521 may supply power to drive the lightingelements 1505.

FIG. 16 is a block diagram of an exemplary system to derive chargingcurrent using the current output from an LED lighting element 1605. TheLED driver 1603 may receive unswitched power from the main power supplythrough an included line interface circuit. Emergency operation may beentered if the main power supply is detected to be interrupted. Thelighting interface included in the LED driver 1603 may be connected to aboost converter 1624 (voltage step-up converter) in parallel to thelighting elements/battery subcircuit. The lighting elements/batterysubcircuit may be comprised of the lighting elements 1605 in parallelwith an on/off switch 1611, further in series with the battery 1621 anda resistor 1628. The boost converter may have additional connections toelectrical points between the light elements 1605 and the battery 1621,and between the battery 1621 and the resistor 1628. The on/off switch1611 may be a series switch, relay, FET, or any suitable switchingcomponents known to those skilled in the art. The current to drive theLED elements 1605 and the current to charge the battery 1621 arecompatible in this exemplary system.

During normal operation, the driver 1603 may control the lightingelements 1605, while the battery 1621 may receive the desired chargecurrent through the connected light elements 1605. The on/off switch1611 may be closed when the elements 1605 are turned off, to allowcharge current to continue to flow to the battery 1621. During emergencyoperation, the battery 1621 may supply power to drive the lightingelements 1605. The boost converter 1624 may increase the voltagesupplied by the battery 1621 to a level adequate to drive the lightingelements 1605. The on/off switch 1611 may be opened during emergencyoperations, to allow the emergency power to flow from the battery 1621to the light elements 1605.

FIG. 17 is a block diagram of an alternate exemplary system to derivecharging current using the current output from an LED lighting element1705. Operation of the system is described below. The configuration ofthe system is similar to that described by FIG. 16, except that a diode1725 may be added in series between the LED elements 1705 and thebattery 1721; a shunt charge 1727 control may be added electrically inparallel to the diode 1725 and the battery 1721; a capacitor 1726 forfiltering may optionally be added in parallel with the battery 1721; andthe additional connections of the boost converter 1724 may be connectedto electrical points between the battery 1721 and the diode 1725, andbetween the battery 1721 and the resistor 1728. The on/off switch 1711may be a series switch, relay, FET, or any suitable switching componentsknown to those skilled in the art. The current to drive the LED elements1705 and the current to charge the battery 1721 need not compatible inthis exemplary system. Algorithms to control the charge current may beimplemented, including using microprocessor control. Charge current maybe terminated using the shunt charge control 1727.

During normal operation, the driver 1703 may drive the lighting elements1705, while the battery 1721 may receive the desired charge currentthrough the connected light elements 1705. The shunt charge control mayregulate the current output from the LED elements 1705, so that battery1721 charge current may be less than the output from LED element 1705.The on/off switch 1711 may be closed when the elements 1705 are turnedoff, to allow charge current to continue to flow to the battery 1721.Emergency operation may be entered if the main power supply is detectedto be interrupted. During emergency operation, the battery 1721 maysupply power to drive the lighting elements 1705. The boost converter1724 may increase the voltage supplied by the battery 1721 to a leveladequate to drive the lighting elements 1705. The on/off switch 1711 maybe opened during emergency operations, to allow the emergency power toflow from the battery 1721 to the light elements 1705.

It will be apparent to those skilled in the art that the describedexemplary systems are generally descriptive and not limiting. Thesystems or components of the systems may be recombined, or substitutedwith generally-known equivalent systems or components, without changingthe inventive aspect. An equivalent component here also includesequivalent inputs and outputs, such as (but not limited to) anequivalent input to indicate status information regarding the main powersupply or the lighting elements. Such equivalent systems are deemed tobe within the scope of the invention, and infringement occurs, if onlyby equivalents, if the equivalent system performs the inventivefunctions claimed.

The foregoing is provided for purposes of illustrating, explaining, anddescribing aspects of the present invention. Further modifications andadaptations to these examples will be apparent to those skilled in theart and may be made without departing from the scope or spirit of theinvention. Different arrangements of the components depicted in thedrawings or described above, as well as components not shown ordescribed are possible. Similarly, some features and subcombinations areuseful and may be employed without reference to other features andsubcombinations. The exemplary systems represented here may beimplemented independently, in conjunction with a different one of thesystems described above, or in conjunction with a system not describedherein.

What is claimed is:
 1. An emergency lighting system, comprising: acombination unit including battery backup components and an LED drivermodule, wherein the combination unit includes a first output comprisingan interface capable of controlling a plurality of LEDs, and a secondoutput capable of providing charging current to an additional batteryunit, wherein the combination unit includes line interface circuitry forconnecting the combination unit to a power supply, wherein thecombination unit includes a status input capable of receivinginformation about a status of the power supply, indicating if the powersupply is interrupted, wherein the battery backup components are capableof receiving a charging current via the line interface circuitry whenthe power supply is uninterrupted, wherein the battery backup componentsprovide DC voltage to the LED driver module during an interruption inthe power supply, and wherein the additional battery unit providesadditional DC voltage to the LED driver module during an interruption inthe power supply.
 2. The emergency lighting system of claim 1, thecombination unit further including a control input configured forreceiving external control signals, wherein the LED driver module isconfigured to control the plurality of LEDs based on the externalcontrol signals when the power supply is uninterrupted.
 3. The emergencylighting system of claim 2, wherein the status input is received via thecontrol input to the combination unit.
 4. The emergency lighting systemof claim 2, wherein the external control signals comprise informationrelated to a test of the system, a test of a subcomponent of the system,or a monitored level of the system.
 5. The emergency lighting system ofclaim 2, wherein the external control signals comprise informationrelated to an input selecting a power status, a dimming level, or acolor level of the plurality of LEDs.
 6. The emergency lighting systemof claim 1, wherein the LED driver module is configured to control theplurality of LEDs via the interface during the interruption in the powersupply and when the power supply is uninterrupted.
 7. The emergencylighting system of claim 1, wherein the combination unit is configuredto provide the charging current to the additional battery unit via thesecond output when the power supply is uninterrupted.
 8. An emergencylighting system, comprising: a combination unit including battery backupcomponents and an LED driver module; and an additional battery unit,wherein the combination unit includes a lighting interface capable ofcontrolling a plurality of LEDs, and a charging interface capable ofproviding charging current to the additional battery unit, wherein thecombination unit includes line interface circuitry for connecting thecombination unit to a power supply, wherein the combination unit isconfigured to receive information about a status of the power supply,indicating if the power supply is interrupted, wherein the batterybackup components are capable of receiving a charging current via theline interface circuitry when the power supply is uninterrupted, andwherein the battery backup components and the additional battery unitprovide DC voltage to the LED driver module during an interruption inthe power supply.
 9. The emergency lighting system of claim 8, thecombination unit further including a control input configured forreceiving external control signals, wherein the LED driver module isconfigured to control the plurality of LEDs based on the externalcontrol signals when the power supply is uninterrupted.
 10. Theemergency lighting system of claim 9, wherein the information about thestatus of the power supply is received via the control input to thecombination unit.
 11. The emergency lighting system of claim 8, whereinthe LED driver module is configured to control the plurality of LEDs viathe lighting interface during the interruption in the power supply andwhen the power supply is uninterrupted.
 12. The emergency lightingsystem of claim 8, wherein the combination unit is configured to providethe charging current to the additional battery unit via the charginginterface when the power supply is uninterrupted.
 13. A method ofcontrolling an emergency lighting system, the method includingoperations comprising: receiving, at a combination unit includingbattery backup components and an LED driver module, a status inputindicating if a power supply to the combination unit is interrupted;providing, via a lighting interface of the combination unit, a controlsignal to a plurality of LEDs; providing, via a charging interface ofthe combination unit, a charging current to an additional battery unit;receiving, by the battery backup components, a charging current when thepower supply is uninterrupted; providing, from the battery backupcomponents, a DC voltage to the LED driver module during an interruptionin the power supply; and providing, from the additional battery unit,additional DC voltage to the LED driver module during the interruptionin the power supply.
 14. The method of claim 13, the combination unitfurther including a control input configured for receiving externalcontrol signals, and the method further comprising controlling, by theLED driver module, the plurality of LEDs based on the external controlsignals when the power supply is uninterrupted.
 15. The method of claim14, wherein the status input is received via the control input to thecombination unit.
 16. The method of claim 14, wherein the externalcontrol signals comprise information related to a test of the system, atest of a subcomponent of the system, or a monitored level of thesystem.
 17. The method of claim 14, wherein the external control signalscomprise information related to an input selecting a power status, adimming level, or a color level of the plurality of LEDs.
 18. The methodof claim 13, wherein the LED driver module is configured to control theplurality of LEDs via the lighting interface during the interruption inthe power supply and when the power supply is uninterrupted.
 19. Themethod of claim 13, wherein the combination unit is configured toprovide the charging current to the additional battery unit via thecharging interface when the power supply is uninterrupted.